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#1
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1969 Rear
My car is a '69 base 400, w/Turbo 400. As it is factory A/C, it should have 3.23 posi. The rpm at freeway speeds lead me to believe the ratio is not 3.23, and I wonder if this rear end is actually a 8.5 due to the ears on the bottom edge.
The tag references "limited slip" lubricant only. I guess I can pull the cover and measure the ring gear diameter and tooth count, but does this look like a factory 8.2?
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1964 Catalina 2+2 4sp, 421 Tri-power 1965 GTO, Roadster Shop chassis, 461, Old Faithful cam, KRE heads 305 CFM, Holley EFI, DIS ignition. 1969 GTO 467, Edelbrock 325 CFM, Terminator EFI 1969 Firebird Convertible |
#2
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most common housing style of the '71-72 8.5 A-body rear, but someone has installed the round cover off a c-clip axle 8.5 rear. should have a cutout style cover & proper gasket. Stronger rearend than any 8.2 rear due to more pinion support.
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Buzzards gotta eat... same as worms. |
#3
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Here is an example of a stock 69 diff
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My Break Away Squad 1969 Fbird (Base, 350 & Sprint Cvt’s - 400HO & TA Hardtops) 1969 LeMans (2dr & 4dr Hardtop and a Cvt) 1969 LeMans Safari 2 seat Wagon 1969 GTO (2 Cvt, 2 Hardtops & Judge Hardtop) 1969 Catalina (3 Cvt’s & a 2dr hardtop) 1969 Ventura 2 Seat Wagon 1969 Executive 4dr Sedan 1969 Bonnie Cvt 1969 Bonnie 3 Seat Wagon (2 of them) 1969 Bonnie Brougham (4dr Hardtop & Cvt) 1969 Grand Prix SJ (2 of them) 1969 2+2 2dr Hardtop (Canadian model) |
#4
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Thanks for the replies. So then I have a 8.5 from a later model A body. I have confirmed it has posi, and using chalk marks on the driveshaft I estimate a 3.08 final drive ratio. I think I'd like to pull the cover for a closer inspection and tooth count. Is there a source for the correct cover, and what lube would be recommended?
It probably also makes sense to get some casting numbers to identify the exact year of the rear end, where would these numbers be located? The car is new to me this past week, so I'm just going over it trying to understand what I have. Here is a pic:
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1964 Catalina 2+2 4sp, 421 Tri-power 1965 GTO, Roadster Shop chassis, 461, Old Faithful cam, KRE heads 305 CFM, Holley EFI, DIS ignition. 1969 GTO 467, Edelbrock 325 CFM, Terminator EFI 1969 Firebird Convertible |
#5
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Nice car, I had one the same color scheme. Car seems to sit too high in back. Maybe the spring perches are different than the stock diff
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My Break Away Squad 1969 Fbird (Base, 350 & Sprint Cvt’s - 400HO & TA Hardtops) 1969 LeMans (2dr & 4dr Hardtop and a Cvt) 1969 LeMans Safari 2 seat Wagon 1969 GTO (2 Cvt, 2 Hardtops & Judge Hardtop) 1969 Catalina (3 Cvt’s & a 2dr hardtop) 1969 Ventura 2 Seat Wagon 1969 Executive 4dr Sedan 1969 Bonnie Cvt 1969 Bonnie 3 Seat Wagon (2 of them) 1969 Bonnie Brougham (4dr Hardtop & Cvt) 1969 Grand Prix SJ (2 of them) 1969 2+2 2dr Hardtop (Canadian model) |
#6
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Good eye. My guess is has something to do with this, likely they had problems clearing the exhaust which is wrapped around the read end, so they raised it up to clear rather than correct the exhaust placement.
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1964 Catalina 2+2 4sp, 421 Tri-power 1965 GTO, Roadster Shop chassis, 461, Old Faithful cam, KRE heads 305 CFM, Holley EFI, DIS ignition. 1969 GTO 467, Edelbrock 325 CFM, Terminator EFI 1969 Firebird Convertible |
#7
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Darbi, The rear is def a '71-72 8.5 A-body. That particular casting center housing was used for two years, & shares same casting number. Have been building HD 8.5 A-body rears for the last 25 years, currently have over two dozen of that particular 8.5 A-body housing in the racks.
When you drain the r/e grease (80/90 w small bottle of GM or Ford Limited Slip additive), take a look at the posi carrier... might post a pic showIng a partial view of the passenger side end of the posi carrier. For many years, several of us rebuilt this style rear with the later & more common #8 or #9 c-clip side gear Limited Slip carriers, and properly rebuilt, set them up with a nice used or new ring & pinion in the bolt-in axle 8.5 rears. The original style "S" spring 8.5 posi carriers for bolt-in axle use aren't nearly as common, as the c-clip version, & its possible your rear began life life most as single track rear, & was assembled at some time with a posi carrier. Need a nice used cutout style cover, feel free and drop me a PM, should be able to grab one.
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Buzzards gotta eat... same as worms. Last edited by 'ol Pinion head; 07-04-2018 at 02:50 PM. |
#8
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Quote:
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1964 Catalina 2+2 4sp, 421 Tri-power 1965 GTO, Roadster Shop chassis, 461, Old Faithful cam, KRE heads 305 CFM, Holley EFI, DIS ignition. 1969 GTO 467, Edelbrock 325 CFM, Terminator EFI 1969 Firebird Convertible |
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